Micro-fluid ejection devices such as ink jet printers continue to experience wide acceptance as economical replacements for laser printers. Micro-fluid ejection devices also are finding wide application in other fields such as in the medical, chemical, and mechanical fields. As the capabilities of micro-fluid ejection devices are increased to provide higher ejection rates, the ejection heads, which are the primary components of micro-fluid ejection devices, continue to evolve and become larger, more complex, and more costly to manufacture.
One significant obstacle to be overcome in micro-fluid ejection head manufacturing process is maintaining the planarity of the ejection device substrate, also referred to as the ejection chip, and the nozzle plate during and after the manufacturing process, particularly when manufacturing ejection heads having an ejection swath dimension of greater than about 2.5 centimeters. The planarity of the ejection chip and the nozzle plate determine the direction in which a fluid such as ink is dispensed. If the nozzle plate is warped or bowed, due to warping or bowing of the underlying ejection device substrate, the desired direction of fluid-jetting is compromised. The planarity of these components may be affected by mismatched coefficients of thermal expansion between the various members of the ejection head, including the nozzle plate, the device substrate, the base support, and any adhesive material used in securing the aforementioned components to one another.
Current manufacturing processes utilize an adhesive die-bonding material to secure the components of the ejection head to one another. However, such adhesives require thermal curing which causes expansion and contraction of the components and may lead to warping or bowing of the ejection device substrate and the nozzle plate. Alterations in the thickness of the adhesive layer or the thickness of the underlying support material have led to only marginal improvements in the planarity of the finished devices. However, current manufacturing processes are limited by the size of the ejection chip. As the demand for larger ejection chips having larger ejection swaths grows, new device construction methods may be required to meet high tolerance manufacturing criteria for such ejection heads.
Accordingly, there is a need for improved structures and methods for making substantially planar micro-fluid ejection heads, suitable for ejection chips having an ejection swath dimension of greater than about 2.5 centimeters.